Enhancing the Rapid Na+-Storage Performance via Electron/Ion Bridges through GeS2/Graphene Heterojunction.

Abstract

Hybridizing carbonous matrix into metal sulfide is confirmed as an effective strategy to enhance electrode conductance and structure stability. However, a comprehensive understanding of the interface reaction mechanism between active materials and carbon substrate is still urgently needed. Based on the band energy theory, a route to enhance the rate ability for electrode is exploited on regulating interfaces of substrates/active heterojunction. Herein, the highly stable Na+-storage performance of GeS2/3DG is delicately designed, where the hierarchical structure is enabled by uniformly overcoating GeS2 nanograins with graphene matrix. Different from the widespread doping route of active materials for fast ion transfer, we focus on the effects of interface regulation on the high-rate Na- ion-storage performance of substrate/active materials. Here, a well-designed interface of the C-Ge bond at the heterointerface induced by hierarchical GeS2/graphene heterojunction is pioneeringly explored, which can result in a fast electron transfer by reducing electron gathering polarization. More importantly, defects in graphene can alleviate the polarization aroused by ion concentration, which not only offers anchoring/doping sites for C-Ge bond but also provides extra ion channels for Na-ion transportation into GeS2. This interface regulation of constructing metal-carbon bonds will shine light on the reaction kinetics and interface stability and contribute to the fundamental understanding of interface reaction mechanisms for metal sulfide anode materials.